Re: GnomeDesktopThumbnail API replacement

[Carlos Garnacho <carlosg gnome org>]

Hey,

On Wed, Jan 17, 2018 at 6:15 PM, Bastien Nocera <hadess hadess net> wrote:
> On Wed, 2018-01-17 at 13:15 +0100, Bastien Nocera wrote:
> > Hey,
> >
> > I wanted to start a discussion about replacing GnomeDesktopThumbnail
> > with an API that would live in the GLib/GTK+ stack.
> <snip>
> > To sum up, here are the questions:
> > - Do we want the API in GTK+ and depending on gdk-pixbuf, even if
> > it's
> > only really meant to be used on "freedesktop" platforms?
> > - Are there specific API entry points that people need besides the
> > current API (including [1]) with async support?
>
> This is the API that I came up with, which could live in either gdk-
> pixbuf, or GTK+, dependency-wise. It might also be small enough to
> copy/paste although I count 15 users of just the C API in Debian
> Codesearch[1], so it might be worth having in a shared library anyway.
>
> typedef enum {
>     GNOME_DESKTOP_THUMBNAIL_FLAGS_NONE = 0,
>     GNOME_DESKTOP_THUMBNAIL_FLAGS_SAVE,  // Whether to save the created (successful or failed) thumbnail to 
> the cache
> } GnomeDesktopThumbnailFlag;
>
> #define GNOME_DESKTOP_THUMBNAIL_FILE_ATTRIBUTES                 \
>         G_FILE_ATTRIBUTE_THUMBNAIL_PATH ","                     \
>         G_FILE_ATTRIBUTE_THUMBNAILING_FAILED ","                \
>         G_FILE_ATTRIBUTE_THUMBNAIL_IS_VALID ","                 \
>         G_FILE_ATTRIBUTE_PREVIEW_ICON ","                       \
>         G_FILE_ATTRIBUTE_TIME_MODIFIED ","                      \
>         G_FILE_ATTRIBUTE_STANDARD_FAST_CONTENT_TYPE
>
> // About @info:
> // NULL means we'll look it up if necessary, otherwise must include
> // GNOME_DESKTOP_THUMBNAIL_FILE_ATTRIBUTES,
> // G_FILE_ATTRIBUTE_STANDARD_CONTENT_TYPE will however be used rather
> // than G_FILE_ATTRIBUTE_STANDARD_FAST_CONTENT_TYPE if present
>
> GdkPixbuf *
> gnome_desktop_thumbnail_generate_thumbnail_sync (GnomeDesktopThumbnailFactory  *factory,
>                                                  GFile                         *file,       // instead of a 
> URI?
>                                                  GFileInfo                     *info,
>                                                  GnomeDesktopThumbnailFlags     flag,
>                                                  char                         **ret_thumbnail_path,
>                                                  GError                       **error);

Maybe having both operations split (#1 generating the thumbnail, #2
loading it as a GdkPixbuf) might help see the layer to which each more
clearly belongs? GdkPixbuf generation from a GFile(Info) might easily
be gdk-pixbuf or gtk+ helpers, thumbnail generation requests might be
into a separate library, or behind a GIO interface.

Cheers,
  Carlos